Modeling and analysis of x-ray emission line images acquired with a prototype model of the XMM Reflection Grating Spectrometer

We obtained monochromatic emission line images with a prototype model of the Reflection Grating Spectrometer for XMM, at the MPE Panter long beam test facility in Munich. We concentrate on the interpretation and analysis of the distribution of dispersed light from single gratings. We present the outline of an exact first order scalar diffraction calculation of the effects of scattering on a grating on the angular profile of the dispersed radiation. Using the resulting predicted scattering profile, we extract the core of the measured profiles for individual gratings, and find good agreement between the shape of these cores and the shape predicted for the long-spatial wavelength slope distribution on the gratings, obtained from interferometry. The widths of the cores meet the specifications for the flatness of the grating substrates.